Display a warning if one of the base package is not installed

src/client/opamState.ml

@@ -351,10 +351,48 @@ let check_opam_version t =
         OpamGlobals.exit 42
     )
 
+let get_compiler_packages t comp =
+  let comp = compiler t comp in
+  let available = OpamPackage.to_map (Lazy.force t.available_packages) in
+
+  let pkg_available, pkg_not =
+    List.partition
+      (fun (n, _) -> OpamPackage.Name.Map.mem n available)
+      (OpamFormula.atoms (OpamFile.Comp.packages comp)) in
+
+  (* check that all packages in [comp] are in [available] except for
+     "base-..."  (depending if "-no-base-packages" is set or not) *)
+  let pkg_not = List.rev_map (function (n, _) -> n) pkg_not in
+  let pkg_not =
+    if not !OpamGlobals.no_base_packages then
+      pkg_not
+    else
+      List.filter (fun n -> not (List.mem n base_packages)) pkg_not in
+  if pkg_not <> [] then (
+    List.iter (OpamPackage.Name.to_string |> OpamGlobals.error "Package %s not found") pkg_not;
+    OpamGlobals.exit 1
+  );
+
+  pkg_available
+
+let check_base_packages t =
+  let base_packages = get_compiler_packages t t.compiler in
+  let missing_packages =
+    List.filter
+      (fun (name,_) -> not (mem_installed_package_by_name t name))
+      base_packages in
+  if missing_packages <> [] then (
+    let names = List.map (fst |> OpamPackage.Name.to_string) missing_packages in
+    OpamGlobals.warning "Some of the compiler base packages are not installed. \
+                         You should run:\n\n    opam install %s\n\n"
+                         (String.concat " " names)
+  )
+
 (* Currently, only check that only installed packages have something
    in $repo/tmp. This could be extended later on. *)
 let consistency_checks t =
   check_opam_version t;
+  check_base_packages t;
   let clean repo_root nv =
     let tmp_dir = OpamPath.Repository.tmp_dir repo_root nv in
     if OpamFilename.exists_dir tmp_dir then (
@@ -682,30 +720,6 @@ let print_env_warning ?(add_profile = false) t =
         opam_root
         add_profile
 
-let get_compiler_packages t comp =
-  let comp = compiler t comp in
-  let available = OpamPackage.to_map (Lazy.force t.available_packages) in
-
-  let pkg_available, pkg_not =
-    List.partition
-      (fun (n, _) -> OpamPackage.Name.Map.mem n available)
-      (OpamFormula.atoms (OpamFile.Comp.packages comp)) in
-
-  (* check that all packages in [comp] are in [available] except for
-     "base-..."  (depending if "-no-base-packages" is set or not) *)
-  let pkg_not = List.rev_map (function (n, _) -> n) pkg_not in
-  let pkg_not =
-    if not !OpamGlobals.no_base_packages then
-      pkg_not
-    else
-      List.filter (fun n -> not (List.mem n base_packages)) pkg_not in
-  if pkg_not <> [] then (
-    List.iter (OpamPackage.Name.to_string |> OpamGlobals.error "Package %s not found") pkg_not;
-    OpamGlobals.exit 1
-  );
-
-  pkg_available
-
 let add_switch root switch compiler =
   log "add_switch switch=%s compiler=%s" (OpamSwitch.to_string switch) (OpamCompiler.to_string compiler);
   let aliases_f = OpamPath.aliases root in